He has summer plots for a number of stations and some sites have plots for each summer going back to 1950. He has used the NWS "monsoon season" definition for these plots - so there can be effects in the data from late season westerly troughs and the data at the ends of the summers are sometimes from after monsoon flow regimes had ended. Regardless, the character of each sites' summer is shown on these graphics in considerable detail (explanations of the plots are at Mike's site).
As a nice example of what's at Mike's page, I've snipped the graphs for summer 2013 for 5 stations and show below - these stations stretch along the Borderlands from El Paso out to Organ Pipe National Monument. Did all the sites have similar monsoon seasons last summer? Hardly. I'll just quickly summarize:
El Paso - wetter than normal especially late in season; Douglas - wettest ever, especially early season; Tombstone - near normal; Tucson - very dry season that ended very early; and Organ Pipe NM - very wet and early season.
So these charts demonstrate very graphically how much variance there can be for a "monosoon season" when viewed from a regional (read mesoscale) perspective. These sites are not very far apart, except perhaps for El Paso way over to the east. Since the summer rainfall is produced by thunderstorms, and sometimes by organized thunderstorm, mesoscale systems, what happens at some spots can be totally unrepresentative of what happens elsewhere, even sometimes at a nearby site.
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